Human sulfur emissions now rival natural sulfur fluxes globally and dominate them locally.

Evidence

Human activity has similarly affected the sulfur cycle. Consumption of fossil fuel, metal smelting, and other activities have been so pervasive that “global fluxes of sulfur induced by humans and those from nature are of comparable magnitude.” Because, moreover, many of those human activities are concentrated in certain heavily industrialized locations, the local contribution of sulfur flow from human activities can substantially exceed the level generated by nature. — Richard J. Lazarus, The Making of Environmental Law, 69